83 million Facebook users are not real

That's a lot of imaginary friends

83 million Facebook users are fake, according to the social network's legal company filings.

Zuck and co reported that 8.7 per cent of the 955 million active Facebook accounts may be dummy or fake profiles.

Around 4.8 per cent of accounts are thought to be duplicate profiles, while 2.4 per cent can be attributed to misclassified accounts (businesses, parodies and, ugh, pets) and 1.5 per cent are described as "undesirable".

Undesirables

These "undesirables" are accounts the break Facebook's rules and include those that send out reams of spam messages and the like.

"We believe the percentage of accounts that are duplicate or false is meaningfully lower in developed markets such as the United States or Australia and higher in developing markets such as Indonesia and Turkey," Facebook said in its filing.

The problem with fake accounts – aside from being annoying for the rest of us - is that they mess with Facebook's ability to serve targeted adverts on the site, as well as skewing the metrics that the social network supplies to its advertisers.